Hydrovac Excavation Waste

Thicken watery hydrovac loads so they can be tipped, stockpiled and hauled without decanting a river of slurry.

Non-destructive digging uses a lot of water, and most of it comes back in the tank. AuraChem matches a grade to the soils and water you usually dig in and helps decide where in your process the polymer goes in.

Discuss Your Application

Hydrovac operator removing soil slurry from an excavation

Why Hydrovac Loads Are Mostly Water

Hydro excavation breaks up soil with pressurised water and vacuums both into a debris tank, so a large share of every load is wash water. In transit the soil drops into a dense layer beneath free water, and a full tank ends up behaving like two different materials when it is emptied.

Clay soils stay suspended and soupy; sandy soils settle quickly and leave clear water on top. Jobs near the coast, or in areas with saline groundwater, add dissolved salt to the mix.

Choosing Where to Treat a Vac Truck Load

Polymer can go into the debris tank before the truck travels, into a receiving pit or tip-off bay at the depot, or into a bin after discharge. Treating in the tank stops the load sloshing on the road but makes mixing and emptying harder; treating at a bay is easier to control but needs somewhere to tip. The right point depends on your trucks, your depot and where the waste goes next.

Thickening Slurry Without Bulking It Up

Hydrovac slurry is close to the ideal case for a superabsorbent: plenty of free water and relatively little additive chemistry. A small addition captures that water as gel and turns a pumpable slurry into a thick paste or crumb that stays where it is tipped.

Because the water is free rather than bound up in clay or mud polymers, the response is usually quick, and far less material goes in than when the same load is bulked out with sawdust, sand or dry soil.

Building a Treatment Routine for Vac Trucks

01Pick typical jobs. Choose loads from your most common soil types rather than one unusual dig.
02Mix the load before sampling. Stir or recirculate so the sample holds settled soil and free water in their real proportions.
03Find the dose for each soil type. Clay-rich and sandy loads often need noticeably different amounts.
04Decide on the treatment point. Weigh road safety, tank discharge and depot layout when choosing tank, bay or bin.
05Give operators a simple rule. A dose per tank volume or a quick visual check lets crews adjust between loads.

Grade Selection for Vacuum Excavation Slurry

Relevant Product

When It May Be Selected

Application-Rate Approach

Relevant ProductAuraSorb 4000 Series

When It May Be SelectedThe usual first choice: the Rapid profile thickens loads quickly enough for busy tip-off bays and short turnarounds.

Application-Rate ApproachDosed per tank load from a figure set in testing, with crews adding a little more for wetter loads and less for sandy ones.

Relevant ProductAuraSorb 8000 Series

When It May Be SelectedFor slurry that will sit in a bin or stockpile before collection, where a firmer, longer-lasting result is wanted.

Application-Rate ApproachTrialled on the same loads as the 4000 Series so the extra retention can be weighed against cost.

Load Characteristics That Change the Dose

Variable

Why it matters

Water-to-soil ratio

Sets the baseline amount of polymer per load

Clay versus sand

Clay stays suspended and soupy; sand drops out fast

Saline or coastal groundwater

Dissolved salt lowers absorption

Settling in transit

Unmixed samples under- or over-state free water

Tank and bay design

Controls how polymer can be added and mixed

Depot or tip requirements

Set how firm the treated material must be

Benefits for Hydrovac Operators

These are potential operational benefits subject to material testing and field or production validation.

Loads stop sloshing, which helps on the road and at tip-off

Much less volume added than sawdust, sand or soil bulking

Treated slurry can be stockpiled instead of held in ponds

Crews can adjust the dose load by load

What Hydrovac Slurry Testing Delivers

Testing on loads from your usual soils gives a starting dose per tank, the time taken to thicken and a description of the treated material. It can also give crews a quick field check, such as how much free water should remain after mixing, so they can top up the dose when a load is wetter than usual.

Hydrovac Slurry Questions

Why do two hydrovac loads need different amounts of polymer?

The water-to-soil ratio and soil type change from job to job. A wet, clay-rich load needs more than a sandy load that has already dropped most of its solids.

Can the polymer go into the debris tank before driving back?

It can, if the load can still be mixed and safely discharged. Gelled material may not empty easily from some tanks, so many operators treat at tip-off instead.

How much does treatment add to disposal volume?

Much less than sawdust or soil bulking, because only a small amount of polymer is added. The exact increase depends on the dose your loads need.

Is slurry from a contaminated site handled differently?

The treatment is the same, but the waste may need sampling and a specific receiving facility. Thickening it does not change the contaminants it contains.